Referring to FIGS. 1 to 4, a conventional hub assembly 10 includes an axle unit 11, a hub shell 12, a driving member 13, a pawl unit 14 and a resilient unit 15.
The axle unit 11 includes an axle member 111, and a plurality of bearings 112 that are mounted on the axle member 111.
The hub shell 12 is mounted on two of the bearings 112 of the axle unit 11, is rotatable about the axle member 111, and has s a surrounding wall 122 and a plurality of installation grooves 124. The surrounding wall 122 defines an inner space 121 therein. The installation grooves 124 are formed in an inner surrounding surface of an end section of the surrounding wall 122. Each of the installation grooves 124 is defined by a respective one of groove-defining surfaces of the surrounding wall 122, and has an opening 123 that communicates spatially with the inner space 121. Each of the groove-defining surfaces has a bottom surface portion 125 that faces the opening 123 of the corresponding one of the installation grooves 124, and a first arc surface portion that is connected to one end of the bottom surface portion 125 in the circumferential direction of the surrounding wall 122 and that defines a first mounting groove portion 126 of the corresponding one of the installation grooves 124, and a second arc surface portion that is connected to an end of the bottom surface portion 125 distal from the first arc surface portion and that defines a second mounting groove portion 127 of the corresponding one of the installation grooves 124.
The driving member 13 is mounted on the bearings 112 of the axle unit 11, is rotatable about the axle member 111, and has a ratchet ring section 131 that extends into the end section of the surrounding wall 122 and that has a plurality of outer teeth 133, and a sprocket section 132 that is disposed out of the hub shell 12. Each of the outer teeth 133 has first and second side surfaces 134, 135 that are opposite to each other in the circumferential direction of the ratchet ring section 131.
The pawl unit 14 includes a plurality of pawls 141 each of which has s a mounting portion 142 and a claw portion 143.
The resilient unit 15 includes a plurality of resilient members 151. Each of the resilient members 151 has a mounting section 152, a positioning section 153 extending from an end of the mounting section 152 for abutting against the bottom surface portion 125 of a respective one of the groove-defining surfaces of the surrounding wall 122, and an urging section 154 extending from another end of the mounting section 152 distal from the positioning section 153 for abutting against a respective one of the pawls 141.
When the mounting portion 142 of each of the pawls 141 is mounted in the first mounting groove portion 126 of a respective one of the installation grooves 124 and when the mounting section 152 of each of the resilient members 151 is mounted in the second mounting groove portion 127 of a respective one of the installation grooves 124 (see FIGS. 1 and 2), the conventional hub assembly 10 serves as a right-hand-drive hub (i.e., the sprocket section 132 of the driving member 13 is located at the right hand side of a bicycle). When the mounting portion 142 of each of the pawls 141 is mounted in the second mounting groove portion 127 of a respective one of the installation grooves 124 and when the mounting section 152 of each of the resilient members 151 is mounted in the first mounting groove portion 126 of a respective one of the installation grooves 124 (see FIGS. 3 and 4), the conventional hub assembly 10 serves as a left-hand-drive hub (i.e., the sprocket section 132 of the driving member 13 is located at the left hand side of a bicycle).
However, in the switching operation of the conventional hub assembly 10 between the right-hand-drive use and the left-hand-drive use, all the pawls 141 and the resilient members 151 need to be uninstalled and reinstalled, resulting in a laborious operation.
U.S. Pat. No. 4,766,772 discloses another conventional hub assembly that is capable of serving as a right-hand-drive hub or a left-hand-drive hub without disassembling of components thereof. However, the conventional hub assembly of U.S. Pat. No. 4,766,772 has redundant transmission mechanisms.